Biology subjects

Tartaglia, M.

Publications and source records attributed to Tartaglia, M..

7 recordsLinked to original sources

bioRxiv2026

Pharmacological BET Protein Inhibition Reverts Niemann-Pick Type C Disease-Associated Changes in Human iPSC-Derived Cortical Neurons

Niemann-Pick type C1 (NPC1) disease is a fatal lysosomal disorder caused by impaired intracellular cholesterol trafficking, leading to progressive neurodegeneration and premature death. Despite advances in disease modelling, therapeutic development remains limited, partly due to the lack of human neuronal systems that accurately recapitulate disease-relevant phenotypes. Here, we generated a patient-specific neuronal model by differentiating induced pluripotent stem cells (iPSCs) carrying the most common NPC1 p.I1061T variant into cortical neurons. These cells exhibit hallmarks of neuronal pathology associated with NPC1 disease, providing a platform to investigate pathological mechanisms and to validate therapeutic candidates in a human context. Using this experimental model, we explored the effects of pharmacological inhibition of bromodomain and extraterminal (BET) proteins. Treatment with the BET inhibitor JQ1 attenuated disease-associated phenotypes, improving neuronal viability and modulating intracellular cholesterol accumulation. Overall, our findings identify BET inhibition as a novel strategy to ameliorate NPC1-associated neuronal pathology and uncover a previously underexplored link between epigenetic regulation and cholesterol homeostasis, highlighting iPSC-derived neurons as a powerful platform for therapeutic discovery.

neuroscience↗

bioRxiv2024

Activation of Wnt/β-catenin signalling by mutually exclusive FBXW11 and CTNNB1 hotspot mutations drives salivary gland basal cell adenoma

Wnt signalling must be just right to promote tumour growth. Basal cell adenoma (BCA) and basal cell adenocarcinoma (BCAC) of the salivary gland are rare tumours that can be difficult to distinguish from each other and other salivary gland tumour subtypes. Due to their rarity, the genetic profiles of BCA and BCAC have not been extensively explored. Using whole-exome and transcriptome sequencing of BCA and BCAC cohorts, we identify a novel recurrent FBXW11 missense mutation (p.F517S) in BCA, that was mutually exclusive with the previously reported CTNNB1 p.I35T gain-of-function (GoF) mutation. These driver events collectively accounted for 94% of BCAs. In vitro, mutant FBXW11 had a dominant negative affect, characterised by defective binding to {beta}-catenin and the accumulation of {beta}-catenin in cells. This was consistent with the nuclear expression of {beta}-catenin observed in BCA cases harbouring the FBXW11 p.F517S mutation and activation of the Wnt/{beta}-catenin pathway. The genomic profiles of BCAC were distinct from BCA, with hotspot DICER1 and HRAS mutations and putative driver mutations affecting PI3K/AKT and NF-{kappa}B signalling pathway genes. A single BCAC, which may represent a malignant transformation of BCA, harboured the recurrent FBXW11 mutation. These findings have important implications for the diagnosis and treatment of BCA and BCAC, which, despite histopathologic overlap, may be unrelated entities.

cancer biology↗

bioRxiv2024

Autoinflammatory patients with Golgi-trapped CDC42 exhibit intracellular trafficking defects leading to STING hyperactivation

Most autoinflammatory diseases are caused by mutations in innate immunity genes. Recently, four variants in the RHO GTPase CDC42 were discovered in patients affected by syndromes generally characterized by neonatal-onset of cytopenia and auto-inflammation, including hemophagocytic lymphohistiocytosis and rash in the most severe form (NOCARH syndrome). However, the mechanisms responsible for these phenotypes remain largely elusive. Here, we show that the recurrent p.R186C CDC42 variant, which is trapped in the Golgi apparatus, elicits a block in both anterograde and retrograde transports, and endoplasmic reticulum stress. Consequently, it favors STING accumulation in the Golgi in a COPI-dependent manner. This is also observed for the other Golgi-trapped p.*192C*24 CDC42 variant, but not for the p.Y64C and p.C188Y variants that do not accumulate in the Golgi. We demonstrate that the two Golgi-trapped CDC42 variants are the only ones that exhibit overactivation of the STING pathway. Consistent with these results, patients carrying Golgi-trapped CDC42 mutants present very high levels of circulating IFN at the onset of their disease. Thus, we report new mechanistic insights on the impact of the Golgi-trapped CDC42 variants. This increase in STING activation provides a rationale for combination treatments for these severe cases.

immunology↗

bioRxiv2022

Alteration of myocardial structure and function in RAF1associated Noonan syndrome: Insights from cardiac disease modeling based on patient-derived iPSCs

Noonan syndrome (NS), the most common among the RASopathies, is caused by germline variants in genes encoding components of the RAS-MAPK pathway. Distinct variants, including the recurrent Ser257Leu substitution in RAF1, are associated with severe hypertrophic cardiomyopathy (HCM). Here, we investigated the elusive mechanistic link between NS-associated RAF1S257L and HCM using three-dimensional cardiac bodies and bioartificial cardiac tissues generated from patient-derived induced pluripotent stem cells (iPSCs) harboring the pathogenic RAF1 c.770C>T missense change. We characterize the molecular, structural and functional consequences of aberrant RAF1 -associated signaling on the cardiac models. Ultrastructural assessment of the sarcomere revealed a shortening of the I-bands along the Z disc area in both iPSC-derived RAF1S257L cardiomyocytes, and myocardial tissue biopsies. The disease phenotype was partly reverted by using both MEK inhibition, and a gene-corrected isogenic RAF1L257S cell line. Collectively, our findings uncovered a direct link between a RASopathy gene variant and the abnormal sarcomere structure resulting in a cardiac dysfunction that remarkably recapitulates the human disease. These insights represent a basis to develop future targeted therapeutic approaches.

cell biology↗

bioRxiv2020

Peptide-based Inhibitors of Protein-Protein Interactions of Src Homology 2 Domain-Containing Phosphatase 2

We developed a new class of inhibitors of protein-protein interactions of the SHP2 phosphatase, which is pivotal in multiple signaling pathways and a central target in the therapy of cancer and rare diseases. Currently available SHP2 inhibitors target the catalytic site or an allosteric pocket but lack specificity or are ineffective on disease-associated SHP2 mutants. Based on the consideration that pathogenic lesions cause signaling hyperactivation due to increased SHP2 association with cognate proteins, we developed peptide-based molecules with low nM affinity for the N-terminal Src homology domain of SHP2, good selectivity, stability to degradation and an affinity for pathogenic variants of SHP2 up to 20 times higher than for the wild-type protein. The best peptide reverted the effects of a pathogenic variant (D61G) in zebrafish embryos. Our results provide a novel route for SHP2-targeted therapies and a tool to investigate the role of protein-protein interactions in the function of SHP2.

biophysics↗

bioRxiv2020

Structural Determinants of Phosphopeptide Binding to the N-Terminal Src Homology 2 Domain of the SHP2 Phosphatase

SH2 domain-containing tyrosine phosphatase 2 (SHP2), encoded by PTPN11, plays a fundamental role in the modulation of several signaling pathways. Germline and somatic mutations in PTPN11 are associated with different rare diseases and hematologic malignancies, and recent studies have individuated SHP2 as a central node in oncogenesis and cancer drug resistance. SHP2 structure includes two Src homology 2 domains (N-SH2 and C-SH2) followed by a catalytic protein tyrosine phosphatase (PTP) domain. Under basal conditions, the N-SH2 domain blocks the active site, inhibiting phosphatase activity. Association of the N-SH2 domain with binding partners containing short amino acid motifs comprising a phosphotyrosine residue (pY) leads to N-SH2/PTP dissociation and SHP2 activation. Considering the relevance of SHP2 in signaling and disease and the central role of the N-SH2 domain in its allosteric regulation mechanism, we performed microsecond-long molecular dynamics simulations of the N-SH2 domain complexed to 12 different peptides, to define the structural and dynamical features determining the binding affinity and specificity of the domain. Phosphopeptide residues at position -2 to +5, with respect to pY, have significant interactions with the SH2 domain. In addition to the strong interaction of the pY residue with its conserved binding pocket, the complex is stabilized hydrophobically by insertion of residues +1, +3 and +5 in an apolar groove of the domain, and interaction of residue -2 with both the pY and a protein surface residue. Additional interactions are provided by hydrogen bonds formed by the backbone of residues -1, +1, +2 and +4. Finally, negatively charged residues at position +2 and +4 are involved in electrostatic interactions with two lysines (Lys89 and Lys91) specific of the SHP2 N-SH2 domain. Interestingly, the MD simulations illustrated a previously undescribed conformational flexibility of the domain, involving the core {beta}-sheet and the loop that closes the pY binding pocket.

biophysics↗

bioRxiv2018

Spatiotemporal analysis for detection of pre-symptomatic shape changes in neurodegenerative diseases: applied to GENFI study

Brain atrophy as measured from structural MR images, is one of the primary imaging biomarkers used to track neurodegenerative disease progression. In diseases such as frontotemporal dementia or Alzheimers disease, atrophy can be observed in key brain structures years before any clinical symptoms are present. Atrophy is most commonly captured as volume change of key structures and the shape changes of these structures are typically not analysed despite being potentially more sensitive than summary volume statistics over the entire structure.\n\nIn this paper we propose a spatiotemporal analysis pipeline based Large Diffeomorphic Deformation Metric Mapping (LDDMM) to detect shape changes from volumetric MRI scans. We applied our framework to a cohort of individuals with genetic variants of frontotemporal dementia and healthy controls from the Genetic FTD Initiative (GENFI) study. Our method, take full advantage of the LDDMM framework, and relies on the creation of a population specific average spatiotemporal trajectory of a relevant brain structure of interest, the thalamus in our case. The residuals from each patient data to the average spatiotemporal trajectory are then clustered and studied to assess when presymptomatic mutation carriers differ from healthy control subjects.\n\nWe found statistical differences in shape in the anterior region of the thalamus at least five years before the mutation carrier subjects develop any clinical symptoms. This region of the thalamus has been shown to be predominantly connected to the frontal lobe, consistent with the pattern of cortical atrophy seen in the disease.

neuroscience↗